// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Copied from strings/stringpiece.h with modifications
//
// A string-like object that points to a sized piece of memory.
//
// You can use StringPiece as a function or method parameter.  A StringPiece
// parameter can receive a double-quoted string literal argument, a "const
// char*" argument, a string argument, or a StringPiece argument with no data
// copying.  Systematic use of StringPiece for arguments reduces data
// copies and strlen() calls.
//
// Prefer passing StringPieces by value:
//   void MyFunction(StringPiece arg);
// If circumstances require, you may also pass by const reference:
//   void MyFunction(const StringPiece& arg);  // not preferred
// Both of these have the same lifetime semantics.  Passing by value
// generates slightly smaller code.  For more discussion, Googlers can see
// the thread go/stringpiecebyvalue on c-users.
//
// StringPiece16 is similar to StringPiece but for kutil::string16 instead of
// std::string. We do not define as large of a subset of the STL functions
// from basic_string as in StringPiece, but this can be changed if these
// functions (find, find_first_of, etc.) are found to be useful in this context.
//

#ifndef KUTIL_STRINGS_STRING_PIECE_H_
#define KUTIL_STRINGS_STRING_PIECE_H_

#include <stddef.h>

#include <iosfwd>
#include <string>

#include "krpc/utility/base_export.h"
#include "krpc/utility/basictypes.h"
#include "krpc/utility/containers/hash_tables.h"
#include "krpc/utility/strings/string16.h"
#include <string_view>

namespace kutil {
    template<typename STRING_TYPE>
    class BasicStringPiece;
    typedef BasicStringPiece<std::string> StringPiece;
    typedef BasicStringPiece<string16> StringPiece16;

    // internal --------------------------------------------------------------------

    // Many of the StringPiece functions use different implementations for the
    // 8-bit and 16-bit versions, and we don't want lots of template expansions in
    // this (very common) header that will slow down compilation.
    //
    // So here we define overloaded functions called by the StringPiece template.
    // For those that share an implementation, the two versions will expand to a
    // template internal to the .cc file.
    namespace internal {
        KUTIL_EXPORT void CopyToString(const StringPiece &self, std::string *target);

        KUTIL_EXPORT void CopyToString(const StringPiece16 &self, string16 *target);

        KUTIL_EXPORT void AppendToString(const StringPiece &self, std::string *target);

        KUTIL_EXPORT void AppendToString(const StringPiece16 &self, string16 *target);

        KUTIL_EXPORT size_t copy(const StringPiece &self,
                                 char *buf,
                                 size_t n,
                                 size_t pos);

        KUTIL_EXPORT size_t copy(const StringPiece16 &self,
                                 char16 *buf,
                                 size_t n,
                                 size_t pos);

        KUTIL_EXPORT size_t find(const StringPiece &self,
                                 const StringPiece &s,
                                 size_t pos);

        KUTIL_EXPORT size_t find(const StringPiece16 &self,
                                 const StringPiece16 &s,
                                 size_t pos);

        KUTIL_EXPORT size_t find(const StringPiece &self,
                                 char c,
                                 size_t pos);

        KUTIL_EXPORT size_t find(const StringPiece16 &self,
                                 char16 c,
                                 size_t pos);

        KUTIL_EXPORT size_t rfind(const StringPiece &self,
                                  const StringPiece &s,
                                  size_t pos);

        KUTIL_EXPORT size_t rfind(const StringPiece16 &self,
                                  const StringPiece16 &s,
                                  size_t pos);

        KUTIL_EXPORT size_t rfind(const StringPiece &self,
                                  char c,
                                  size_t pos);

        KUTIL_EXPORT size_t rfind(const StringPiece16 &self,
                                  char16 c,
                                  size_t pos);

        KUTIL_EXPORT size_t find_first_of(const StringPiece &self,
                                          const StringPiece &s,
                                          size_t pos);

        KUTIL_EXPORT size_t find_first_of(const StringPiece16 &self,
                                          const StringPiece16 &s,
                                          size_t pos);

        KUTIL_EXPORT size_t find_first_not_of(const StringPiece &self,
                                              const StringPiece &s,
                                              size_t pos);

        KUTIL_EXPORT size_t find_first_not_of(const StringPiece16 &self,
                                              const StringPiece16 &s,
                                              size_t pos);

        KUTIL_EXPORT size_t find_first_not_of(const StringPiece &self,
                                              char c,
                                              size_t pos);

        KUTIL_EXPORT size_t find_first_not_of(const StringPiece16 &self,
                                              char16 c,
                                              size_t pos);

        KUTIL_EXPORT size_t find_last_of(const StringPiece &self,
                                         const StringPiece &s,
                                         size_t pos);

        KUTIL_EXPORT size_t find_last_of(const StringPiece16 &self,
                                         const StringPiece16 &s,
                                         size_t pos);

        KUTIL_EXPORT size_t find_last_of(const StringPiece &self,
                                         char c,
                                         size_t pos);

        KUTIL_EXPORT size_t find_last_of(const StringPiece16 &self,
                                         char16 c,
                                         size_t pos);

        KUTIL_EXPORT size_t find_last_not_of(const StringPiece &self,
                                             const StringPiece &s,
                                             size_t pos);

        KUTIL_EXPORT size_t find_last_not_of(const StringPiece16 &self,
                                             const StringPiece16 &s,
                                             size_t pos);

        KUTIL_EXPORT size_t find_last_not_of(const StringPiece16 &self,
                                             char16 c,
                                             size_t pos);

        KUTIL_EXPORT size_t find_last_not_of(const StringPiece &self,
                                             char c,
                                             size_t pos);

        KUTIL_EXPORT StringPiece substr(const StringPiece &self,
                                        size_t pos,
                                        size_t n);

        KUTIL_EXPORT StringPiece16 substr(const StringPiece16 &self,
                                          size_t pos,
                                          size_t n);
    } // namespace internal

    // BasicStringPiece ------------------------------------------------------------

    // Defines the types, methods, operators, and data members common to both
    // StringPiece and StringPiece16. Do not refer to this class directly, but
    // rather to StringPiece, or StringPiece16.
    //
    // This is templatized by string class type rather than character type, so
    // BasicStringPiece<std::string> or BasicStringPiece<kutil::string16>.
    template<typename STRING_TYPE>
    class BasicStringPiece {
    public:
        // Standard STL container boilerplate.
        typedef size_t size_type;
        typedef typename STRING_TYPE::value_type value_type;
        typedef const value_type *pointer;
        typedef const value_type *const_pointer;
        typedef const value_type &reference;
        typedef const value_type &const_reference;
        typedef ptrdiff_t difference_type;
        typedef const value_type *const_iterator;
        typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

        static const size_type npos;

    public:
        // We provide non-explicit singleton constructors so users can pass
        // in a "const char*" or a "string" wherever a "StringPiece" is
        // expected (likewise for char16, string16, StringPiece16).
        BasicStringPiece() : ptr_(NULL), length_(0) {
        }

        BasicStringPiece(const value_type *str)
            : ptr_(str),
              length_((str == NULL) ? 0 : STRING_TYPE::traits_type::length(str)) {
        }

        BasicStringPiece(const STRING_TYPE &str)
            : ptr_(str.data()), length_(str.size()) {
        }

        BasicStringPiece(const std::basic_string_view<value_type> &str)
            : ptr_(str.data()), length_(str.size()) {
        }

        BasicStringPiece(const value_type *offset, size_type len)
            : ptr_(offset), length_(len) {
        }

        BasicStringPiece(const BasicStringPiece &str, size_type pos, size_type len = npos)
            : ptr_(str.data() + pos), length_(std::min(len, str.length() - pos)) {
        }

        BasicStringPiece(const typename STRING_TYPE::const_iterator &begin,
                         const typename STRING_TYPE::const_iterator &end)
            : ptr_((end > begin) ? &(*begin) : NULL),
              length_((end > begin) ? (size_type) (end - begin) : 0) {
        }

        // data() may return a pointer to a buffer with embedded NULs, and the
        // returned buffer may or may not be null terminated.  Therefore it is
        // typically a mistake to pass data() to a routine that expects a NUL
        // terminated string.
        const value_type *data() const { return ptr_; }
        size_type size() const { return length_; }
        size_type length() const { return length_; }
        bool empty() const { return length_ == 0; }

        void clear() {
            ptr_ = NULL;
            length_ = 0;
        }

        explicit operator std::basic_string_view<value_type>() {
            return std::basic_string_view<value_type>(data(), size());
        }

        BasicStringPiece &assign(const BasicStringPiece &str, size_type pos, size_type len = npos) {
            ptr_ = str.data() + pos;
            length_ = std::min(len, str.length() - pos);
            return *this;
        }

        void set(const value_type *data, size_type len) {
            ptr_ = data;
            length_ = len;
        }

        void set(const value_type *str) {
            ptr_ = str;
            length_ = str ? STRING_TYPE::traits_type::length(str) : 0;
        }

        value_type operator[](size_type i) const { return ptr_[i]; }

        void remove_prefix(size_type n) {
            ptr_ += n;
            length_ -= n;
        }

        void remove_suffix(size_type n) {
            length_ -= n;
        }

        // Remove heading and trailing spaces.
        void trim_spaces() {
            size_t nsp = 0;
            for (; nsp < size() && isspace(ptr_[nsp]); ++nsp) {
            }
            remove_prefix(nsp);
            nsp = 0;
            for (; nsp < size() && isspace(ptr_[size() - 1 - nsp]); ++nsp) {
            }
            remove_suffix(nsp);
        }

        int compare(const BasicStringPiece<STRING_TYPE> &x) const {
            int r = wordmemcmp(
                ptr_, x.ptr_, (length_ < x.length_ ? length_ : x.length_));
            if (r == 0) {
                if (length_ < x.length_) r = -1;
                else if (length_ > x.length_) r = +1;
            }
            return r;
        }

        STRING_TYPE as_string() const {
            // std::string doesn't like to take a NULL pointer even with a 0 size.
            return empty() ? STRING_TYPE() : STRING_TYPE(data(), size());
        }

        // Return the first/last character, UNDEFINED when StringPiece is empty.
        char front() const { return *ptr_; }
        char back() const { return *(ptr_ + length_ - 1); }
        // Return the first/last character, 0 when StringPiece is empty.
        char front_or_0() const { return length_ ? *ptr_ : '\0'; }
        char back_or_0() const { return length_ ? *(ptr_ + length_ - 1) : '\0'; }

        const_iterator begin() const { return ptr_; }
        const_iterator end() const { return ptr_ + length_; }

        const_reverse_iterator rbegin() const {
            return const_reverse_iterator(ptr_ + length_);
        }

        const_reverse_iterator rend() const {
            return const_reverse_iterator(ptr_);
        }

        size_type max_size() const { return length_; }
        size_type capacity() const { return length_; }

        static int wordmemcmp(const value_type *p,
                              const value_type *p2,
                              size_type N) {
            return STRING_TYPE::traits_type::compare(p, p2, N);
        }

        // Sets the value of the given string target type to be the current string.
        // This saves a temporary over doing |a = b.as_string()|
        void CopyToString(STRING_TYPE *target) const {
            internal::CopyToString(*this, target);
        }

        void AppendToString(STRING_TYPE *target) const {
            internal::AppendToString(*this, target);
        }

        size_type copy(value_type *buf, size_type n, size_type pos = 0) const {
            return internal::copy(*this, buf, n, pos);
        }

        // Does "this" start with "x"
        bool starts_with(const BasicStringPiece &x) const {
            return ((this->length_ >= x.length_) &&
                    (wordmemcmp(this->ptr_, x.ptr_, x.length_) == 0));
        }

        // Does "this" end with "x"
        bool ends_with(const BasicStringPiece &x) const {
            return ((this->length_ >= x.length_) &&
                    (wordmemcmp(this->ptr_ + (this->length_ - x.length_),
                                x.ptr_, x.length_) == 0));
        }

        // find: Search for a character or substring at a given offset.
        size_type find(const BasicStringPiece<STRING_TYPE> &s,
                       size_type pos = 0) const {
            return internal::find(*this, s, pos);
        }

        size_type find(value_type c, size_type pos = 0) const {
            return internal::find(*this, c, pos);
        }

        // rfind: Reverse find.
        size_type rfind(const BasicStringPiece &s,
                        size_type pos = BasicStringPiece::npos) const {
            return internal::rfind(*this, s, pos);
        }

        size_type rfind(value_type c, size_type pos = BasicStringPiece::npos) const {
            return internal::rfind(*this, c, pos);
        }

        // find_first_of: Find the first occurence of one of a set of characters.
        size_type find_first_of(const BasicStringPiece &s,
                                size_type pos = 0) const {
            return internal::find_first_of(*this, s, pos);
        }

        size_type find_first_of(value_type c, size_type pos = 0) const {
            return find(c, pos);
        }

        // find_first_not_of: Find the first occurence not of a set of characters.
        size_type find_first_not_of(const BasicStringPiece &s,
                                    size_type pos = 0) const {
            return internal::find_first_not_of(*this, s, pos);
        }

        size_type find_first_not_of(value_type c, size_type pos = 0) const {
            return internal::find_first_not_of(*this, c, pos);
        }

        // find_last_of: Find the last occurence of one of a set of characters.
        size_type find_last_of(const BasicStringPiece &s,
                               size_type pos = BasicStringPiece::npos) const {
            return internal::find_last_of(*this, s, pos);
        }

        size_type find_last_of(value_type c,
                               size_type pos = BasicStringPiece::npos) const {
            return rfind(c, pos);
        }

        // find_last_not_of: Find the last occurence not of a set of characters.
        size_type find_last_not_of(const BasicStringPiece &s,
                                   size_type pos = BasicStringPiece::npos) const {
            return internal::find_last_not_of(*this, s, pos);
        }

        size_type find_last_not_of(value_type c,
                                   size_type pos = BasicStringPiece::npos) const {
            return internal::find_last_not_of(*this, c, pos);
        }

        // substr.
        BasicStringPiece substr(size_type pos,
                                size_type n = BasicStringPiece::npos) const {
            return internal::substr(*this, pos, n);
        }

    protected:
        const value_type *ptr_;
        size_type length_;
    };

    template<typename STRING_TYPE>
    const typename BasicStringPiece<STRING_TYPE>::size_type
    BasicStringPiece<STRING_TYPE>::npos =
            typename BasicStringPiece<STRING_TYPE>::size_type(-1);

    // MSVC doesn't like complex extern templates and DLLs.
#if !defined(COMPILER_MSVC)
    extern template class KUTIL_EXPORT BasicStringPiece<std::string>;
    extern template class KUTIL_EXPORT BasicStringPiece<string16>;
#endif

    // StringPiece operators --------------------------------------------------------

    KUTIL_EXPORT bool operator==(const StringPiece &x, const StringPiece &y);

    inline bool operator!=(const StringPiece &x, const StringPiece &y) {
        return !(x == y);
    }

    inline bool operator<(const StringPiece &x, const StringPiece &y) {
        const int r = StringPiece::wordmemcmp(
            x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
        return ((r < 0) || ((r == 0) && (x.size() < y.size())));
    }

    inline bool operator>(const StringPiece &x, const StringPiece &y) {
        return y < x;
    }

    inline bool operator<=(const StringPiece &x, const StringPiece &y) {
        return !(x > y);
    }

    inline bool operator>=(const StringPiece &x, const StringPiece &y) {
        return !(x < y);
    }

    // StringPiece16 operators -----------------------------------------------------

    inline bool operator==(const StringPiece16 &x, const StringPiece16 &y) {
        if (x.size() != y.size())
            return false;

        return StringPiece16::wordmemcmp(x.data(), y.data(), x.size()) == 0;
    }

    inline bool operator!=(const StringPiece16 &x, const StringPiece16 &y) {
        return !(x == y);
    }

    inline bool operator<(const StringPiece16 &x, const StringPiece16 &y) {
        const int r = StringPiece16::wordmemcmp(
            x.data(), y.data(), (x.size() < y.size() ? x.size() : y.size()));
        return ((r < 0) || ((r == 0) && (x.size() < y.size())));
    }

    inline bool operator>(const StringPiece16 &x, const StringPiece16 &y) {
        return y < x;
    }

    inline bool operator<=(const StringPiece16 &x, const StringPiece16 &y) {
        return !(x > y);
    }

    inline bool operator>=(const StringPiece16 &x, const StringPiece16 &y) {
        return !(x < y);
    }

    KUTIL_EXPORT std::ostream &operator<<(std::ostream &o,
                                          const StringPiece &piece);

    // [ Ease getting first/last character of std::string before C++11 ]
    // return the first/last character, UNDEFINED when the string is empty.
    inline char front_char(const std::string &s) { return s[0]; }
    inline char back_char(const std::string &s) { return s[s.size() - 1]; }
    // return the first/last character, 0 when the string is empty.
    inline char front_char_or_0(const std::string &s) { return s.empty() ? '\0' : s[0]; }
    inline char back_char_or_0(const std::string &s) { return s.empty() ? '\0' : s[s.size() - 1]; }
} // namespace kutil

// Hashing ---------------------------------------------------------------------

// We provide appropriate hash functions so StringPiece and StringPiece16 can
// be used as keys in hash sets and maps.

// This hash function is copied from kutil/containers/hash_tables.h. We don't
// use the ones already defined for string and string16 directly because it
// would require the string constructors to be called, which we don't want.
#define HASH_STRING_PIECE(StringPieceType, string_piece)                \
  std::size_t result = 0;                                               \
  for (StringPieceType::const_iterator i = string_piece.begin();        \
       i != string_piece.end(); ++i)                                    \
    result = (result * 131) + *i;                                       \
  return result;

namespace
KUTIL_HASH_NAMESPACE {
#if defined(COMPILER_GCC)

    template<>
    struct hash<kutil::StringPiece> {
        std::size_t operator()(const kutil::StringPiece &sp) const {
            HASH_STRING_PIECE(kutil::StringPiece, sp);
        }
    };

    template<>
    struct hash<kutil::StringPiece16> {
        std::size_t operator()(const kutil::StringPiece16 &sp16) const {
            HASH_STRING_PIECE(kutil::StringPiece16, sp16);
        }
    };

#elif defined(COMPILER_MSVC)

inline size_t hash_value(const kutil::StringPiece& sp) {
  HASH_STRING_PIECE(kutil::StringPiece, sp);
}
inline size_t hash_value(const kutil::StringPiece16& sp16) {
  HASH_STRING_PIECE(kutil::StringPiece16, sp16);
}

#endif  // COMPILER
} // namespace KUTIL_HASH_NAMESPACE

#endif  // KUTIL_STRINGS_STRING_PIECE_H_
